F. Maggiore,Y. T. Jou & S. Kim
Department of Endodontics, School of Dental Medicine, University of Pennsylvania, Philadelphia, USA.

Introduction.
The goal of root canal treatment is to clean the root canal system as thoroughly as possible and to fill it in all its dimensions (Cohen & Burns 1998). In depth knowledge of the root canal anatomy of each tooth is crucial in order to reach this goal.
The maxillary first molar most commonly has three or four cana , with one canal in both the palatal and distobuccal roots and one or two in the mesiobuccal root. The incidence of a mesiolingual canal has been reported between 18% and 96.1% (Hartwell and Bellizzi 1982, Kulild & Peters 1990). Cecic et al. (1982), Jacobsen & Nii (1994), and Stone & Stroner (1981) found cases of maxillary first molars in which the palatal canal contained one orifice, a bifurcated canal and two separate foramina. Beatty (1984) presented a case of a maxillary first molar with five cana , three of which were located in the mesiobuccal root. Bond et al. (1988) reported a case of a maxillary first molar with six cana : two cana  with separate foramina in the mesiobuccal root, two cana  with separate foramina in the distobuccal root, and two cana  joining in the apical third of the palatal root. Hu mann (1997) presented a maxillary first molar with two distinct cana  in the distobuccal root. Slowey (1979) showed a case of a maxillary molar with two palatal cana  and separate foramina. Martinez-Berna & Ruiz-Badanelli (1983) reported three cases of maxillary first molars with six cana : three cana  in the mesiobuccal root, two in the distobuccal root and one in the palatal root and finally, Wong (1991) reported a case in which the palatal root had a single canal orifice, a trifurcation in the apical third and three separate foramina. This information is summarized in Table 1.

Table 1. Reported canal configuration of the maxillary first molar.


S: separate canalswith separate foramina.
J:Canals joining in the apical one-third.

The present case report describes a case of a maxillary first molar with a canal configuration not yet reported in the literature. This tooth had a trifurcation in the palatal canal in the apical third with three separate foramina, two distinct cana  in the mesiobuccal root and a single canal in the distobuccal root.

A 19-year-old African-American male presented to the Emergency Clinic of the University of Pennsylvania, School of Dental Medicine, with the chief complaint of a toothache in his left maxilla. Due to deep decay in tooth #14 a diagnosis of symptomatic irreversible pulpitis with a normal periapex was made (Fig. 1). The patient’s medical history was non-contributory and an emergency pulpectomy was performed at the first visit. During examination with an operating microscope (JedMed/Kaps, St Louis, MO, USA) the anatomy of the first maxillary left molar was determined as follows: two cana  in the mesiobuccal root, one canal in the distobuccal root and a large palatal canal bifurcating approximately 4 mm from the working length with two separate foramina (Fig. 2). These five cana  were instrumented and medicated with Ca(OH)2. At the third visit all cana  were filled by a modified MicrosealTM technique (Analytic Endodontics, Orange, California, USA) and with zinc-oxide-eugenol cement (Grossman type). The final obturation showed some of the obturation material flowing in an additional canal located between the two bifurcating palatal cana  (Fig. 3). Doubt about the long-term success of the case was raised and it was decided to re-enter the palatal canal to evaluate the possible third apical branch. The gutta-percha was removed from the palatal canal up to the bifurcation level using a System B tip (Analytic Endodontics). This area was carefully inspectioned again under the operating microscope at high magnification (16–25_). This examination of the palatal root revealed the two cana  filled with gutta-percha and between them, in a more buccal position, a third canal orifice. Under the microscope it was possible to insert a size 15 K-file and the existence of a third foramen was confirmed using an electronic apex locator (Root ZX, J. Morita MFG. Corporation, Kyoto, Japan). A new radiograph was taken with a size 20 K-file in place (Fig. 4). The radiograph clearly showed the presence of a third palatal canal. This canal was instrumented and filled using the modified Microseal technique (Analytic Endodontics). A temporary restoration with IRM was placed and a permanent restoration was advised. The postoperative radiograph showed six separate cana  and six separate foramina of the tooth (Fig. 5). Twenty months later the patient was recalled for a follow-up. At the clinical examination the tooth was asymptomatic and the radiographic examination revealed normal periapical tissue (Fig. 6). However, the tooth had not yet been permanently restored at this recall visit and the patient was again instructed to return to his dentist for the restoration.

Figure 1. Preoperative radiograph.



Figure 2. Working length determination of five canals.



Figure 3. Obturation of five canals. Note obturation material flowing between the two bifurcating palatal canals.



Figure 4. Working length determination of the sixth canal.



Figure 5. Postoperative X-ray showing six separate canals with six separate foramina.



Figure 6. A total of 20 months follow-up. The radiograph shows the integrity of the root canal therapy and a normal periapex.

Discussion.
This article presents a case of a maxillary first molar with an unusual number and arrangement of cana . Usually, the interpretation of the radiograph along with a careful inspection of the pulp chamber floor by probing and by proper visualization allows the operator to understand the root canal configuration. In the present case, it was possible, based on radiographic interpretation, to visualize the bifurcated palatal canal. It was only after the first postoperative radiograph that a possible third palatal canal was suspected. The use of the operating microscope and the electronic apex locator were crucial both for the detection and for the management of the three cana  in the palatal root.

References.

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